The major goal of this research is to elucidate the function and interrelationship of the several enzymes and cofactors involved in glycine metabolish, particular the model systems available in Peptococcus glycinophilus and Clostridium acidiurici, but whose distribution and significance in other organisms, including animal and humans, is becoming more apparent. Four enzymes related to the oxidative cleavage of glycine will receive particular emphasis: (a) the pyridoxal phosphate-containing glycine decarboxylase; (b) the lipoic acid-containing electron transfer protein; (c) the FAD-containing dihydrolipoate dehydrogenase; and (d) the tetrahydrofolate-requiring alpha- carbon transferase. The concerted function of these enzymes is to remove the carboxyl group of glycine as CO2, making the methylene carbon available for the condensation with a second glycine molecule to form serine. In the process the electrons removed during decarboxylation are transferred via the lipoate and FAD enzymes to DPN. By reaction with still other enzymes the serine thus formed is converted to pyruvate, thence acetyl-CoA and acetyl-PO4, the major energy source for the cells. In this study the enzymes will be separated by salt fractionations, ion exchange and molecular seive chromatography, electrofocusing and ultracentrifugation. The newly discovered function of lipoic acid in glycine decarboxylation, and the availability of this enzyme in sufficient quantities to allow amino acid sequencing will permit us to determine the primary structure of the electron transfer protein, and also us to investigate the interaction of pyridoxal phosphate and lipoate in one phase of the reaction, and of lipoate and FAD in another phase. Furthermore, the ready availability of the lipoate enzyme ad the ease with which lipoate may now be assayed (due to procedures developed in our laboratory), coupled with the fact that we have determined some of the biosynthetic precursors, makes it now possible for us to investigate in detail the biosynthesis of lipoic acid.